For the last 22 years, we have demonstrated, using rats in Pavlovian preparations, that many "deficits" in learned behavior (e.g., overshadowing, blocking, and effects of preexposure to conditioned or unconditioned stimuli [CSs or USs]) are due, at least in part, to processes that occur at the time of expression, rather than during acquisition as is assumed by most contemporary models of associative learning. Our data prompted us to reject the traditional associative position, which states that over a series of training trials subjects learn only a few summary statistics, and encourages the view that subjects encode a rich, nearly veridical representation of their experiences. To direct our research, we developed the "comparator hypothesis," which is a performance-focused rule for translating knowledge acquired through simple spatio-temporal contiguity into behavior. As we and others published ever more data problematic for the traditional associative emphasis on acquisition processes, researchers started acknowledging the importance of post-training information processing. Some investigators concurred with our performance-focused account of these findings. But other researchers modified existing acquisition-focused models to allow new learning about a previously trained CS on post-training trials on which the CS is absent. These revised acquisition-focused models can account for much of the data that we had viewed as uniquely supportive of our performance-focused account. This stimulated us to extend the comparator hypothesis, formalize it in a mathematical implementation (SOCR), and design experiments for which these new acquisition-focused models and the extended comparator hypothesis make divergent predictions. The proposed experiments will discriminate between these two types of models, thereby contributing to a more complete understanding of learning, memory, and acquired behavior, and directing the agenda of scientists concerned with the neurophysiological basis of learning and memory.